1. Field of the Invention
The present invention relates to performance evaluation of electronic devices and, more particularly, to degradation evaluation of electronic display devices.
2. Description of the Related Art
Electronic devices whether audio or video are commonplace. They are utilized in a myriad of applications within many fields of technology. Video applications range from TV, video games, and computers, to the display of data for monitoring various occurrences or events within many, varied environments, e.g. machining, robotics, aircraft instrument display, computer simulation and analysis, nuclear power plant monitoring and regulation, and the like. Audio applications range from telecommunications and transmission links, to recorders and the like.
In the later exemplary uses described above, electronic displays convey visual information and data to the observer such as current or operating conditions, various stages of warning conditions, results, etc. It is upon this information and data that the observer must make decisions regarding the monitored environment. Often, these devices display critical event and condition data which must be conveyed to the observer for immediate consideration, possibly resulting in a consequential action taking place. In the case of many video devices, color plays an important role in conveying the visual information to the observer. It is therefore important that the information presented to the observer through the video device be readable. Thus, visibility becomes an important consideration in the application of electronic displays.
One such critical event display is in the application of video display devices in airplane cockpits. Whether the airplane is commercial, private, or government, video displays are utilized to provide current, real-time data which must be seen and comprehended by the pilot.
Eventually, all electronic devices undergo a deterioration of performance over their effective lifetime. The rate and degree of deterioration or degradation of performance of the device is influenced by many factors. Generally though, with human senses, it is difficult to determine up to the actual point of failure, whether or not the performance of an electronic device has degraded and to what degree.
The evaluation of the performance characteristics of electronic displays for determining display degradation is essential for assuring adequate and accurate conveyance of the visual information, especially in critical environment applications.
Thus, because of the need for receiving intelligible information via video display devices, the video display devices utilized for conveyance of such information must be tested periodically for performance degradation.
It has been known to test signal transmission by use of test signals in order to appraise the quality of signal transmission. Results were analyzed using specialized equipment such as a waveform monitor (oscilloscope) and, for NTSC encoded color, the vectorscope. Although this type of testing indicated performance deterioration or degradation of the transmitting equipment, it did not indicate whether the receiving video device was functioning properly or not.
Manufacturers, video repair establishments, and end users performed tests on the video devices in order to appraise the performance thereof. Such testing was conducted utilizing various patterns, created to reveal possible problems. Analysis was performed by visual inspection and with some limited photometric and colormetric equipment.
Because of the history of the development of video display devices, Cathode Ray Tubes (CRT's) have generally been the target of performance testing. CRT testing has traditionally focused on problems such as convergence of the red, green, and blue primaries in a color CRT. Convergence, the precise alignment of the red, green, and blue electron beams in a shadow mask tube, is evaluated by the position of the separate red, green, and blue dots or pixels to significant accuracy by use of CCD sensor arrays to inspect a small area at a time. Such systems are very complex and do not address all of the characteristics of a CRT which can degrade and affect performance. Further, such performance testing systems are not applicable to video display devices such as LCD, plasma, fluorescent, LED, or other non-CRT display technology.
Automated testing of video display devices has traditionally been to devise a method to automatically decipher information contained within traditional and complex test signals and patterns. These test signal and patterns may be, for example, gray Scale, Multiburst, Encoded Color Bar, and Sin-Squared combinations and patterns such as the EIA Resolution Test Chart, and the SMPTE Test Pattern per RP-133. These signals and patterns are constituted in a rather complex manner with a multiplicity of test stimuli in order to make transmission of the test information most efficient and to make visual observation and evaluation as speedy as possible.
Generally, pattern generators are utilized to create the relatively complex images for the automatic testing. However, the prior art automatic video testing systems require a closed-loop system wherein the sensor, which interprets what is shown on the display under test, must be separately informed of the display content, and the test being performed. Thus, the display stimulus must be of a proper, predetermined content and the processor interpreting sensor signals must be separately informed as described above. Also, most prior art systems do not consider specific setup situations, or the type or content of the test being performed. Further, prior art automatic video testing systems often utilize human intervention and evaluation of test stimuli.
Because of the shortcomings of the prior art, it is desired to have automated testing of all types of electronic video displays, which is without human subjectivity, and is an open loop system.